This study presents ab initio thermochemical estimates for a series of Ti and Si compounds, for which there are no experimental data. It also offers insights in the Ti and Si chemistry, which turns out to be quite different than that of the isovalent C;Silicon compounds are intimately involved with chemical vapour deposition (CVD) processes, as well as the technology of new materials;Ti plays a very important role in catalytic processes like alkene polymerization. Its reaction with small hydrocarbons, is a phenomenon very little understood and depends on the oxidation of the metal centre and the type of hydrocarbon. There is a very limited number of studies, experimental or theoretical, on the reaction of neutral metal atoms with small hydrocarbons. The understanding of such a process would also help understanding the formation of Ti-metcars, one of new the materials;The system B/H2 is one of great theoretical and practical importance. It is subject to interstate crossing and strong diabatic effects are expected to play a crucial role in it use as a potential rocket fuel.